Components of Other Gains (Losses), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gain (losses)	$ 29	$ (179)	$ 426	$ (753)
Gains (losses) on Trading Securities	1,011	1,115	94	(8,348)
Other, net	(21)	(611)	11	(245)
Other gains (losses), net	$ 1,019	$ 325	$ 531	$ (9,346)